The terms vitrification, oxidation, water smoking, and flashing are all associated with: Select one: Select one:

a. spanning openings with bricks or other masonry units.

b. cleaning bricks after masons install them.

c. chemical processes involved in mortar hydration.

d. firing bricks in a kiln.

e. chemical reactions during the installation of foamed-in-place insulation.

Answer is option D.

The terms vitrification, oxidation, water smoking, and flashing are all associated with firing bricks in a kiln.

Explanation:

Brick is one of the building materials made from the clay. The manufacturing process of brick include;

1) Winning - It is the process of mining of clay and its transportation to the manufacturing site.

2) Preparation - It includes the crushing and grinding of clay and later mixing them into a uniform raw material.

3) Forming/Molding - It is the process of mixing water with the clay mix and mold it into the desired shape. The plasticity of the clay depends on the amount of water used.

4) Drying - The process of removing the moisture from wet clay by drying it through evaporation.

5) Firing and Cooling - Firing is the process of burning the clay in a kiln and it usually requires 40 - 150 hours. The different stages in firing are;

Water smoking or dehydration stage - It is a process in which free water retained in the pores of the clay after drying gets evaporated under a high temperature of 400-650°C and the clay loses its plasticity. Some of the carbonate minerals are eliminated. Oxidation - This process occurs at a very high temperature of 650-900°C in which the ferrous iron is oxidized to the ferric form and the remaining carbon is eliminated. Vitrification - This process occurs at a very high temperature of 900 - 1100°C for low melting clay and 1000-1250°C for high melting clay, where the clay is transformed into a soft molten mass as a result of an increase in temperature. It gradually loses the shape and transforms into a glassy structure after cooling. Flashing - In this process, the fire in the kiln is regulated in such a way that it causes a reduction in the kiln temperature and the cooling process begins which produces color variations in bricks.

6) Drawing - It is the process involving the unloading of the kiln after cooling and packing of the bricks for further shipment.